The present invention concerns a control apparatus for pneumatic evacuation and/or water valves, operated by vacuum pressure and used in a vacuum sewerage system, particularly for pneumatically operated sanitary appliances, such as vacuum closets, urinals or wash basins. The control apparatus comprises an activating element, such as a button, which is integrated in a housing and can be moved relative to this housing against a force to operate a control valve comprising a valve disc and a valve piston and transmitting vacuum pressure from a vacuum source to the evacuation and water valves.
Control apparatus for pneumatic evacuation and/or water valves are used for example in combination with vacuum closets in boats or trains. Since activating elements and control valves are integrated in separate housings, conduits are required to connect them. Another disadvantage is that evacuation cycles can start even if vacuum strength is not sufficient for efficient evacuation. This results in malfunction of the vacuum sewerage system. In addition, there is the danger that vacuum is continuously transmitted to the evacuation or water valves if the activating element, such as push button, remains in its activating position, e.g. due to malfunction or maloperation.
The present invention addresses these problems and provides a control apparatus of the initially mentioned kind, particularly for sanitary appliances operated by vacuum pressure, which is very compact and prevents continuous transmittal of vacuum to the evacuation and water valves in case of malfunction or maloperation of the activating element. In addition, an evacuation cycle shall be performed only if the vacuum is sufficiently strong. Finally, it shall be able to keep the water valve open longer than the evacuation valve, as is required particularly if used in combination with vacuum closets.
According to the present invention, the problems are solved by means that the valve piston of the control valve is moved by a diaphragm separating a first and a second chamber within the housing, that the first chamber is connected to the vacuum source and is connectable through the control valve to the evacuation and/or water valves, that the second chamber is connected with atmospheric air after the activating element has been moved against the force into the housing and returned to its original position, and that a spring drives the diaphragm towards the second chamber, whereby the diaphragm is moved against the spring force by a sufficient pressure difference between the second and first chamber and opens the control valve.
The control apparatus, according to the present invention, guarantees that vacuum pressure from the vacuum source is transmitted to the evacuation or water valve only after the activating element has been moved from its first to its second position and returned to its original position. The control valve can be opened for transmittal of vacuum to the evacuation or water valves only if the pressure difference between the second and first chamber is sufficient to move the diaphragm against the spring force. If the difference between atmospheric pressure in the second chamber and vacuum pressure in the first chamber is not sufficient to move the diaphragm against the spring force from its first position, closing the control valve, to its second position, opening the control valve, the first control valve remains closed, and evacuation cannot be performed.
The same applies if the actuating element, e.g. push button, remains jammed in its pressed position. In this case, the second chamber cannot be connected with the atmosphere. The activating element interacts with a control piston sealing a connection between the second chamber and the atmosphere as long as the activating element is pressed against the force into the housing, and is moved by the activating element while this returns to its original position to open the connection between the second chamber and the atmosphere.
In other words, the activating element must be moved from its original position and must return to its original position to open the control valve, to transmit vacuum to the evacuation or water valve, and to open them. The control valve is opened only if the vacuum strength in the second chamber is sufficient for the evacuation procedure.
It is further proposed that the control piston is engaged by the diaphragm and returned to its original position, closing the connection between the atmosphere and the second chamber, while the diaphragm is moved from its first position, closing the control valve, to its second position, opening the control valve. When the connection between the second chamber and the atmosphere is closed, the second chamber is evacuated through a connection between the first and the second chamber. This connection is preferably provided through the valve piston of the control valve.
A spring element, forcing the activating element towards its original position, encompasses the control piston to keep the control apparatus compact.
For further improvement of the control apparatus according to the present invention, a restrictor means is provided interacting with the diaphragm and/or the valve piston of the control valve such that movement of the diaphragm and opening of the control valve can take place only if the vacuum strength is sufficient for evacuation of wastewater through the evacuation valve. In other words, movement of the diaphragm, opening of the control valve and transmittal of vacuum from the first chamber to the evacuation and water valves is restricted to a condition of sufficient vacuum strength. The restrictor means may comprise a magnet located in the second chamber and interacting with a metal plate fixed to the diaphragm. Restricting forces can be adjusted by selection of appropriate magnets and metal plates.
While the first control valve closes the first chamber, ambient air pressure is transmitted through the control valve to the evacuation or water valves and keeps them closed.
The present invention provides an extraordinary compact control apparatus. The activating element, the control piston, the first and second chambers, separated by the diaphragm, and the control valve are arranged in a single cylindrical housing, whereby the activating element is located on its front, while connections for conduits to the vacuum source and the evacuation and water valves are located on its back. The control piston and the valve piston are preferably arranged coaxially with the cylinder axis of the housing.
An orifice is provided on the back of the housing, connects the first chamber with the atmosphere and is closed by the control valve while vacuum is transmitted to the evacuation or water valves.
According to another proposal of the present invention, a throttling means, such as a nozzle, is provided within the conduit to the water valve for delayed closing of the water valve relative to the evacuation valve. By this means, water can be supplied after the evacuation procedure is finished. This is particularly useful for closets and urinals. The present invention also involves a method for controlling the operation of a valve.